Had this happen to me first cycle. I had to stop because my fever flared up twice in two weeks each time after a pin. If you don't have a fever you don't have the flu. If it's a low grade fever and goes away in a few days I wouldn't worry about it since it's flu season anyways and you may have gotten it anywhere. When is your next injection? I'm assuming Monday if that's the case you should be feeling better by then if not skip the inject until you do and pin again. If you flare up again, i'd reconsider the cycle altogether. Get on pct in two weeks from last pin and call it a day.